Harumi is the entity Kotarou met in that holeWhen the light catches her hair when Kotarou first sees her, the color actually changes to that of the woman for a second.
- Jossed - Harumi is the reincarnation of a princess from Theia's world.
The entity is a ghostHer message to Kotarou was entirely an illusion. Note that, despite being on an archaeological dig, Kotarou's accidental finding of what appears to be an intact shrine goes totally unnoticed. However, meeting with Kotarou has somehow freed the entity, and thus set events for her return/reincarnation in motion. Kotarou and the girls will all have a part in this.
Kotarou will go time travellingIt has been foreshadowed pretty hard that he is the real, original Blue Knight and Kiriha's Onni-chan. Plus whatever the entity in the cave was, she was waiting for him. Seems likely he is going to have to go back and become the author of his own fate.
- Confirmed - he travels back in time and meets Alaia Kua Forthorthe in Volume 7.